Past innovations and future challenges
Ecological sanitation
21ST CENTURY
(Picture: EcoSan)
This EcoSan toilet applies the concept of ecological sanitation (ecosan) – safe local processing of human waste to reduce pathogens and recycle nutrients to be used in agriculture or other purposes.
(Picture: EcoSan)
​
Another EcoSan toilet, being installed in South Africa, shows the wide pipe leading back from the pan to an accessible chamber. Each time the toilet lid is opened and closed, a helical screw in the pipe rotates a little, slowly moving solid waste backward until the dried residue falls into a bag in the chamber, for collection and use as fertiliser.
Various toilet designs apply ecosan principles. Some are very similar to Moule’s earth closet of 1860: a little dry soil is dropped onto faeces after use, which helps promote composting. Others use worms or bacterial to reduce pathogen loads and speed up decomposition of the waste, or digest the waste in specialised containers to produce biogas, which can be used to fuel stoves and for other similar purposes.
Many involve urine-diverting pans; these keep the faeces drier for better decomposition, while allowing the nitrogen- and phosphorus-rich urine to be collected and used to improve soils. Urine diversion can also prevent hormones and other chemicals from entering soil or water supplies.
(Picture: ecosan cape)
​
Most share a number of features. They are typically dry toilets – no water is needed to flush them, and they don’t require connection to a sewer system. They require sealed containers of varying sizes, and may take a bit more time and effort to install and maintain, but need to be emptied less frequently than pit toilets, because the volume of waste reduces as it decomposes. The end product should be largely odour- and pathogen-free though, depending on the method, ecosan may not remove all pathogens, including parasite eggs, from the resulting waste.
Again, they’re suitable for a variety of environments, including urban areas – though the fertiliser end product is more useful if access to rural areas is straightforward.